Indicator summary

Summary of indicator structure and function

Definition and/or background

The following is from Fulton et al 2004a -

This is a model-derived measure, which represents the sum of all flows into and out of the components (species or groups) in the system. It includes all imports and exports of useable materials and energy (including catch, migration and the like), respiration and flows to and from any detrital components of the ecosystem. On a per area basis, it is a better indicator of system size than biomass (Ulanowicz 1986) and is useful for the comparison of flow networks (i.e. system at different times of fished vs unfished systems) (Christensen et al. 2000). The basis for this usefulness is that over the last twenty years ecologists (e.g. Ulanowicz 1986) have developed an interpretation of ecosystem structure and function that is based on thermodynamics and information theory. Under this scheme system growth is characterised by flows not total biomass and thus throughput is a better measure of the system size, with throughput increasing as the system grows (Christensen 1994). Unfortunately, calculation of throughput will not be possible for all systems due to its data requirements (ICES 2001A).

Attribute

Ecosystem structure and function

Purpose

Ecosystem size

Data required

The following is from Fulton et al 2004a -

• Biomass per species (or group) recorded (preferably at least for the main components of the ecosystem and through time or vs. some reference area)
• Taxonomic data (or at least categorisation of the main components of the system)
• Catch data of species in fishery
• Mortality estimates for each group
• Consumption / Biomass estimates for each group
• Diet data

Ecosystem applicability

The following is from Fulton et al 2004a -

Should be applicable in all ecosystems.

Robustness

The following is from Fulton et al 2004a -

Medium to low: determination of the throughput of the system is data intensive, and by itself probably not very informative. However, if it can be estimated, and as part of an integrated set of indicators (e.g. in conjunction with an empirical indicator or other model based indicators such as Relative Ascendency, which is a measure of system development), it could be very useful for characterising the system and how it has changed. As a model-derived indicator it is reliant on the assumptions used to construct the underlying model and the data used to parameterise and initialise the model. This makes it unsuitable as a predictive indicator, but this does not prevent it from being an informative indicator, especially if it is part of a larger suite of indicators.

References

Fulton, E.A., Smith, A.D.M., Webb, H., and Slater, J. (2004a) Ecological indicators for the impacts of fishing on non-target species, communities and ecosystems: Review of potential indicators. AFMA Final Research Report, report Number R99/1546.

References that Fulton et al uses for this indicator:

Christensen, V. 1994. On the behaviour of some goal functions for ecosystem development. Ecological Modelling 75/76: pp 37-49.

Christensen, V., C.J. Walters, and D. Pauly. 2000. ECTOPATH with ECOSIM: a user’s guide. October 2000 edition. Fisheries Centre, University of British Columbia, Vanouver, Canada and International Centre for Living Aquatic Resources Management, Penang, Malaysia.

ICES. 2001a. Report of the Working Group on Ecosystem Effects of Fishing Activities. International Council for the Exploration of the Seas, CM 2001/ACME: 09, 102pp.

Ulanowicz, R.E. 1986. Growth and development: ecosystem phenomenology. Springer-Verlag, New York, 203pp.

Background reading

Fulton, E.A., Fuller,M., Smith, A.D.M., and Punt, A. (2004) Ecological indicators of the ecosystem effects of fishing: Final report. AFMA Final Research Report, report Number R99/1546.

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